body{
    background-color: #f4f4f4;
    color: #555;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 16px;
    line-height: 1.6em;
    margin: 0;
}

.container{
    width: 80%;
    margin: auto;
    overflow: hidden; /*no scroll bar even if sth goes outside the container*/
}

#main-header{
    background-color: coral;
    color: cornsilk;
}

/*flow the nav bar*/
#navbar{
    background-color: #333333;
    color: white;
}

#navbar ul{
    padding: 0;
    list-style: none;
}

#navbar li{
    display: inline; /*makes the navbar in one line*/
}

/*change the navbar color to make it more friendly*/
#navbar a{
    color: white;
    text-decoration: none;
    font-size: 18px;
    padding-right: 20px;
}

#navbar a:hover{
    color: yellow;
}

#navbar a:active{
    color: chartreuse;
}

#showcase{
    background-image: url('../images/showcase.jpg');
    background-position: center right;
    min-height: 300px; /*makes the height will growth (more responsive)*/
    margin-bottom: 30px;
    text-align: center;
}

#showcase h1{
    color: white;
    font-size: 50px;
    line-height: 1.6em;
    padding-top: 30px;
}

#main{
    float: left;
    width: 70%;
    padding: 0 30px;
    box-sizing: border-box;
}

#sidebar{
    float: right;
    width: 30%;
    background-color: #333;
    color: white;
    padding: 10px;
    box-sizing: border-box;
}
#main-footer{
    background-color: #333;
    color: white;
    text-align: center;
    padding: 20px;
    margin-top: 40px;
}


/*when the windows size is thinner than 600, the main box and the side bar may no longer floating*/ 
@media(max-width: 600px){
    #main{
        width: 100%;
        float: none;
    }

    #sidebar{
        width:100%;
        float: none;
    }
}